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Far Northern California

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Modoc County, California

Glass Mountain


Modoc - COUNTY

4 miles of dirt fire road to reach- PAVEMENT
Mountain, dirt, - CURVES

Rare, fill whenever possible: MacDoel, Burney, McCloud, Bieber - GAS



Quick Ride: Remote mountain of obsidian glass lava flow found near the Oregon border in northeast corner of California. Reached by three-miles of dirt road overlooking Lava Beds National Monument.

A Mountain of Glass

Twenty-five years ago, I had a Gousha Road Atlas of the United States.


It was this large 11”x9” soft-cover book of every state in America. One large double-sided page for each state. I had used it for my 6000-Miles in 8 Days ride across America a few months earlier and things were looking up.


I had acquired a ’90 Yamaha FJ1200. And I had only received my new license plate that read 'PASHNIT' after scribbling out 26 different 7-letter versions of the word 'passionate' days earlier. The FJ1200 was my first foray into a larger displacement sportbike and a significant departure from my mile-eating ’83 Yamaha Venture. I had put 60,000 miles on the Venture over the last three years. Still didn’t own a car, the Venture got ridden rain or shine. The new FJ1200 came with a spiffy Corbin Gunfighter solo saddle and a Tour Master magnetic tank bag. Now all I needed was a destination to get acquainted. I opened up the Gousha Road Atlas and flipped to the page for California and began running my finger across the page grid square by grid square.

Lava Beds National Monument
Tionesta Rd in the Modoc National Forest

And there it was way up in the top right corner of California, near the Oregon border.

Glass Mountain.


Glass Mountain? What is that? A mountain of glass, perhaps. Roads looked sketchy. Were there roads to find this mountain? Paved or dirt, couldn’t tell, the map wasn’t detailed enough. But there it was, conveniently labeled for my discovery. It was a label and a dot.

Well kids, back in the olden days, there was no internet to magically say ‘Hey Google, where’s Glass Mountain?” In the olden days, you purchased a book from Whitehorse Press on ‘Interesting things to see in <insert your state here>.


And I did have a book by famous motorcycle author Clement Salvadori, but it wasn’t mentioned in there. The several other books I had on my newly adopted state made no mention of a mountain made of glass.

And the more I thought about it, and the more I stared at my new bike, the more the label on the map gnawed at my senses. And my curiosity began to consume me.

It was a simpler time. No wife, no kids, no mortgage. Within days of discovering that label, I took off on my new ’90 Yamaha FJ1200 armed with nothing more than a sleeping bag and a couple bucks for gas to find this magical mountain of glass

Road toGlass Mountain is found at a hairpin on Tionesta Rd

Plan: Get on bike. Go north. That was the extent of my planning.

If you wanted to go seek out a strange and magical place (I hoped), you got on the bike and went to seek it out. Adjacent to this Glass Mountain label on my map was Lava Beds National Monument, well that sounded interesting. And the road looked paved through the national monument. I’d wing the rest.

After reaching Lava Beds National Monument and sleeping on the ground at the campground, I checked out the Lava Tubes and hiked to the top of a cinder cone volcano called Schonchin Butte, discovering a fire lookout at the top at 5253 ft. I then rode south out of Lava Beds and made my way east with a bit of guesswork and intuition to find my mystery destination.

Lava Beds National Monument Rd led south and then intersected with Tionesta Rd. Tionesta Rd (FR 44N01) was paved, although narrow and no center line east of Tionesta.


It’s worth noting, Tionesta looks like a town on the map, but it’s nothing more than two campgrounds for RVs. There is a camp store here, but the closest gas is 30 miles away at a card lock in Tulelake from Tionesta so plan accordingly with your fuel range. Gas up well in advance of entering this region - there is no gas anywhere. Bikes with 100-mile range, carry spare fuel.

Road to Glass Mountain

Heading west away from Tionesta, the road conditions are overly inviting on Tionesta Road. Tionesta Rd is also known as National Forest 97. Long straights, long views, deserted road, it was perfect. As you hit the railroad tracks six miles west of Hwy 139, there is a gravel pit along the tracks for the Great Northern Railroad, slow down for this crossing, quite a bump.  I doubt you'll see very many people except the occasional camper headed for Medicine Lake, and do watch out for logging trucks pulling out onto the road.  You'll see the dirt on the road kicked off from the tires.

Dirt Road to Glass Mountain includes great views

In front of you is the mountain.  You can see it looming ever closer. This region is flat and predominantly treeless, vegetation is high-desert sparse. This northeast corner of California only gets about 10 inches of rain for the entire year. The mountain looms in front of you, as the elevation begins to climb into the Modoc National Forest. The vegetation quickly changes as the elevation breaches the 5000 ft level and climbs into a welcoming pine forest, while the smell of the evergreen is divine.

Glass Montain Lava Flow

There are several splinter roads that intersect and head off into the forest, however, there is only one paved road.


Note you can reach the north side of Glass Mountain via the dirt Forest Rd 44N08 which is 9.2 miles west of Hwy 139 right after the Burlington Northern Santa Fe Railway tracks and Glass Mountain Pumice, a pumice and rock processing company. Yes, you can hike to the summit of 7622 ft Glass Mountain, but you’ll have to use FR 44N08, park at the base, and hike up a ridgeline to get to the actual summit of the lava flow.

Glass Mountain lava flows from above

Climbing up the mountain through several switchbacks, the turn-off for Glass Mountain is found at a hairpin 19 miles west of Hwy 139 and 9 miles east of the Volcanic Legacy Scenic Byway (Powder Hill Rd / FR 49) junction. Continuing north from this junction will take you to Medicine Lake and a small camping and resort area centered around the 7920 ft lake, but Forest Road 49 is not paved north of Medicine Lake at FR 77.


Note despite the earlier mention of little rain, much of Lava Beds NM is over 4000 feet and snow may linger. The mountains create their own weather and the east side is in the rain shadow. I tried riding NF 97 road many years later in late May, and was rather surprised (I shouldn’t have) to find Tionesta Rd still impassible due to snow, resulting in being rather disappointed and having to backtrack to Tionesta. (below)

Snow still blocks Tionesta Rd in late May

If you approach Glass Mountain from the south, you’ll need to ride Hwy 89 from Mount Shasta or Burney. If you have the time, do not miss McArthur-Burney Falls. This waterfall is one of the eighth wonders of the world- well, California at least. There’s no river supplying this massive waterfall, water is shooting straight out of a rock wall. Flowing through the ground until it exits this rock face at such a velocity, it creates a massive waterfall that is quite stunning. And perfect to visit on a hot summer day.

Approaching Glass Mountain from the south at Hwy 89, start out from Bartle (which is little more than a label on the map), and turn north on Harris Spring Rd. Note this road splits into a Y 4.4 miles north of Hwy 89. A turn north onto Powder Hill Rd / NF 49 will take you onto the Modoc Volcanic Scenic Byway. This turn is signed as NF 49. Staying to the right onto Powder Hill Rd / NF 49 will take you to Medicine Lake (dead end) or Glass Mountain. Staying straight on Harris Spring Rd at the intersection will provide a paved forest road all the way over this low range to Macdoel (gas) on Hwy 97, but you’ll be on the wrong road if you’re trying to reach Glass Mountain or Medicine Lake.

17.8 Miles from the Harris Springs Rd/Powder Hill Rd junction is the Jot Dean Ice Cave and, as the name implies, is a cave with ice in it – year-round. While not the only ice cave in this volcanic region, the Jot Dean Ice Cave is mere feet from the road and is a quick walk to check out this strange phenomenon where a cave contains significant amounts of perennial (year-round) ice. No paved paths or handy stairs, bring a flashlight and layer up for the dramatic drop in temperature, then climb down the rocks into the cave mouth to check out the ice.

After 29 miles from Hwy 89, NF 97 takes a turn to the east here at a broad intersection in the forest. The Medicine Lake resort area is one mile north. A turn east here will take you 4.6 miles to the turn-off for Glass Mountain.

A sign in a hairpin for FR 43N99 is the turn north to reach Glass Mountain and this dirt fire road turned out to be a dusty but a well graded wide road that actually makes a full loop around Lyon Peak, 7995 ft and Red Shale Butte, el 7334 ft.

One-mile up, FR43N99 pops over the ridgeline are stunning views to the east over the Nevada border. The lava flow is three miles north up the dirt fire road.

Powder Hill Rd to Glass Mountain
Powder Hill Rd to Glass Mountain
Glass Mountain Lava Flow

For all my curiosity, and lack of planning, the Glass Mountain label on the map turned out to be a mountain of obsidian rock. The obsidian here are large boulders of black glass. Some were smooth boulders of black glass, others a dirty brown color. Walking paths have been cut into the lava flow, wide enough for a UTV. You came all this way, take a stroll. The 7622 ft Glass Mountain itself is visible due north and accessible from Tionesta Rd via Forest Rd 44N08 which is 9.2 miles west of Hwy 139. Yes, you can hike to the summit of Glass Mountain, but you’ll have to take the aforementioned FR 44N08, park at the base, and hike up a ridgeline to get to the actual summit of the lava flow. There are paths carved into the lava flow due north to the base of Glass Mountain.

Glass Mountain lava flow is relatively recent, geologically speaking, it erupted a mere 950 years ago, however not the explosive sort of eruption you associate with volcanoes like Mt St Helens or Mt Lassen. Rather, obsidian forms when the lava oozes from calderas in the earth surface, cooling rapidly into glass. Leaving behind lava flows, but not the sort of smooth flows you see on the news in Hawaii, rather this field of lava looks several stories thick, and is a jagged flow of boulders pushing its way down the mountain side.

Walking trails cut into the lava flow
Obsidian boulders at Glass Mountain

1000 Years in geological time is a mere blink, and there are a few lone trees that have eked out a life growing in the lava field, but overall, it’s lifeless.


In the end, it was just a pile of rock. But that’s not the point.


Seeking out a label on a map was the element that made it exciting. The remoteness of the location gave Glass Mountain an added quality of reverence, creating a sense of smallness. Even while walking across the lava flow, you can’t get a sense of how large it is until you view aerial photos of the flow.


Additionally, when arriving at the lava flow, you begin to gather a more three-dimensional sense of how large the lava flow is. The flow is a wall of rock that’s quite obviously being pushed through the forest by some unseen earthen force. A force that can push mountains of rock. Fascinating stuff.

There is a small dirt parking area where you first encounter the lava flow along Forest Road 43N99, but if you ride down the road another ½ mile, you’ll encounter another entry point into the lava flow. The walking paths connect between these two parking spots, and it is possible to walk across the flow on the dirt path.


While admittedly,  the majority of the rock in the lava field isn't the black shiny kind, the few piles of obsidian boulders like the ones pictured below are truly fascinating. If you took geology in high school or college, you held onto a tiny egg sized piece of shiny black rock. Scale that up to basketball sized boulders of the stuff. True wonderment. The rock is disjointed and disorganized, ranging from piles of it, to huge holes you can climb into.

Obsidian boulders at Glass Mountain

There are two other Glass Mountains in California, one is located in Inyo County near Mono Lake along Hwy 120 & the Benton-crossing Loop, and one can hike to the summit. Glass Mountain, on the Inyo National Forest, is one of the tallest peaks in Mono County, California. The peak lies 20 miles southeast of the shoreline of Mono Lake and is the highest point on the four-mile-long, sinuous Glass Mountain Ridge. There is also Little Glass Mountain found along Davis Rd near the Little Mount Hoffman Fire lookout (via 43N77).


Glass Mountain in Modoc County is well worth checking out, another interesting place in California to experience on your motorcycle. Don’t let three miles of dusty dirt road dissuade you.


There are no services here, no people, no gift shops, nothing. But that’s why you came in the first place.


All it took was a label on a map.

Closing Thoughts


It might be a bit anti-climactic, after all, in end, Glass Mountain turned out to be just a pile of rock. But the first time I came up here as a young man in my late 20s, it was a pilgrimage, a wanderlust, a mission to see what that label on the map was all about. Seeking out a point on the map was exciting, it was addictive, it was alluring. It was the curiosity that got me here.


I learned something. I felt something. But more importantly, I found something. That sound of silence atop this mountain, so deserted and remote, I could ride for an hour or more without seeing another soul. And the rock wasn’t just any old rock, the boulders of glass obsidian were fascinating, unusual and have been sitting here undisturbed for 1000 years.

Standing atop this mountain for the first time, I set the 35mm camera up on a rock and took the photo at right. It became a favorite for many years and decades later I can still feel myself sitting atop that mountain listening to the sound of the wind in the trees.

Contemplation at Glass Mountain

Glass Mountain - Photo Gallery

MORE INFO: Glass Mountain

Ride it on a Pashnit Tour
34 Miles - LENGTH

 Remote backroads, Dirt to reach the lava flow - PAVEMENT

 McCloud, Tulelake- GAS

Mount Shasta, Fall River Mills, Tule Lake - LODGING


41°38′46″N 121°19′41″W - Tionesta
41°15′28″N 121°49′16″W - Bartle
41°34′54″N 121°35′56″W - Glass Mountain

FR 44N08 (dirt)

Powder Hill Rd / NF 49
Harris Spring Rd (paved to Macdoel)

Lava Beds National Monument Rd (paved)

Lava Beds National Monument

Eagles Nest RV Park
Hawks Nest Tionesta RV Park

Locatoin of Modoc County, California

Topo Maps

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